Prior publications authored by the present inventors and assigned to the present assignee proposed simulating film grain in a decoded video stream by first filtering grain out the image before compression. The video stream undergoes compression and subsequent transmission to a decoder for receipt along with a message containing information about the film grain that was present in the stream prior to compression. Upon receipt of the compressed video stream and grain-containing message, the decoder decodes the compressed stream and then restores the original grainy appearance of the image by simulating the film grain based on the content of the grain information message. The film grain message can take the form of a Supplemental Enhancement Information (SEI) message accompanying the coded video stream.
Simulating film grain in this manner provides large bit-rate savings for high quality applications where the film grain preservation becomes important. However, this method of simulating film grain increases the decoder complexity since the decoder must reproduce and blend the film grain with the decoded video stream as specified by the transmitted film grain information message.
Thus, a need exists for a technique for simulating film grain that overcomes the disadvantages of the prior art.